It takes about 5,730 years for half of a sample of radiocarbon to decay back into nitrogen.It takes another 5,730 for half of the remainder to decay, and then another 5,730 for half of what's left then to decay and so on.
It must be 1 carbon 14 half-life (or 5730 years) old.' This is the basic idea behind carbon dating. In the atmosphere, cosmic rays smash into normal carbon 12 atoms (in atmospheric carbon dioxide), and create carbon 14 [email protected] you Carbon Dating Radiocarbon dating , or carbon dating , is a radiometric dating method that uses the naturally occurring radioisotope carbon-14 (14C) to determine the age of carbonaceous materials up to about 58,000 to 62,000 years. uncalibrated, radiocarbon ages are usually reported in radiocarbon years "Before Present" (BP), "Present" being defined as AD 1950.Such raw ages can be calibrated to give calendar dates.After plants die or they are consumed by other organisms (for example, by humans or other animals) the 14C fraction of this organic material declines at a fixed exponential rate due to the radioactive decay of 14C.Comparing the remaining 14C fraction of a sample to that expected from atmospheric 14C allows the age of the sample to be estimated.
That can be extended to perhaps 100,000 years by accelerator techniques for counting the carbon-14 concentration .